After printing is performed on paper, it is next delivered to a sheeter which cuts the paper into sheets, and then to a deliverer, which retards the speed of the individual sheets and then transports the individual sheets of paper to a stacker. Delivering light-weight paper, such as pharmaceutical paper, is difficult because the paper has very little rigidity. Most typical deliverers use a combination of pulleys and wheels and belts to control the paper. This method often causes the paper to buckle, jamming the delivery unit.
As an alternative to belts, a vacuum sheeter uses a plurality of vacuum belts disposed between a pair of pulleys, having a vacuum chamber directly beneath their top surface, and a plurality of apertures within the belts in communication with the vacuum chamber, to control the paper. A first set of vacuum belts delivers the paper from the sheeter at a high speed. A vacuum roller is located at the end of the vacuum belts. The vacuum roller includes a plurality of rows of apertures, with each row being substantially parallel to the longitudinal axis of the cylinder. The holes are in communication with the hollow interior of the cylinder, which in turn is in communication with a vacuum system. Each row corresponds to the stop position for one sheet. A second set of vacuum belts, similar to the first set but moving at a slower speed, is located after the vacuum roller, and may use the vacuum roller as one of its pulleys. The individual paper sheets are carried out of the sheeter at a high speed by the first set of vacuum belts, where they are stopped by the vacuum roller. Each set of holes on the vacuum roller will stop the trailing edge of one sheet, before the cylinder indexes to the next position to stop the next sheet. The sheets are thereby stacked, and the second set of vacuum belts carries them to their next destination.
Although the vacuum sheeter eliminates the jamming problem, it tends to cause light-weight paper to rise into the air as air gets caught underneath the paper. The speed at which the sheeter can be operated is limited by the tendency of the lead edge of the paper to fly up.
Accordingly, there is a need for an improved deliverer including a means for preventing the leading edge of the paper from flying up as it exits the sheeter. Additionally, there is a need for an improved deliverer which avoids the jamming problems of other types of deliverers. There is a further need for a deliverer capable of running at high speed, thereby maximizing it productivity and reducing the overall costs of printing, cutting, and stacking the paper.